The U.S. Justice Department's antitrust unit will fight in court to prevent the acquisition of T-Mobile by AT&T, U.S. Attorney General Eric Holder told lawmakers.

Speaking in reply to a question posed by Senator Herb Kohl, chair of the Senate antitrust subcommittee, Holder acknowledged he was 'recused' in the case, but asked whether the Justice Dept. would be in it "for the long haul".

Holder said: "People in the antitrust division are committed to seeing this through", adding that a trial team is "ready and eager to go to court", reports Reuters.

In August, the Justice Dept. stepped in by beginning legal proceedings against AT&T, in a bid to prevent the $39 billion merger from going ahead, which would make AT&T the largest wireless carrier in the United States.

Verizon, currently holding the market lead, followed by Sprint in third place, are both also suing to stop the deal from going ahead.

But AT&T is fighting back, desperate to in its T-Mobile opponent to propel itself into the top spot. The wireless giant argues that it will give back more to the U.S. in terms of infrastructure and greater consumer service.

CNET also reports that the merger will create around 100,000 jobs for the U.S. economy, according to the Communications Workers of America.

Deutsche Telekom, the German-owner of T-Mobile USA, is as reported yesterday requires a 'Plan B' in case the deal does fall through from legal action. Third-quarter results on Thursday will focus on the future of T-Mobile, in particular in the U.S. market, and whether or not the sell-off is even a viable option for the parent company.